The long range goal of my research program is to study the organization and coordinate expression of the structural genes encoding muscle-specific proteins synthesized during muscle development in Drosophila melanogaster. Towards this goal, we have screened a recombinant genomic DNA Drosophila library using a muscle-specific 32P-cDNA probe. From a total of 285 plaque-purified DNA clones complementary to myogenic cDNA, we have identified and partially characterized 12 clones to determine the proteins encoded. Six of these clones code for proteins which co-migrate in two-dimensional polyacrylamide gels with proteins that appear to be developmentally regulated during myogenesis. We are currently characterizing these clones more fully by restriction enzyme analysis and in situ hybridization to polytene chromosomes. These clones will also be used as probes to analyze mRNA synthesis and processing during myogenesis.